This invention relates to monitoring the vanadium content of the streams in a refinery process and more particularly, to the measurement of vanadium content by measuring the intensity of selected peaks of the ESR spectra.
The vanadium content of a refinery feedstock is one of the principal variables which must be monitored in a refinery process. The type of catalyst used and the severity of cracking are determined in large part by vanadium content of the feedstream. The analysis of vanadium content in refinery feedstocks has typically been done by wet chemical analysis. This is a time consuming procedure and the resultant vanadium content is not typically available in a form which can be used for on-line control of the refinery process.
Electron spin resonance spectroscopy (ESR) has become an important analysis tool. Typical laboratory spectrometers using this technique are described in Assenheium, "Introduction to Electron Spin Resonance," Plenum Press, 1967, pp. 52-56. ESR has been used for the analysis of feedstocks in refinery processes. It is known that certain peaks in the ESR spectra indicate the presence of vanadium in the asphaltenes in refinery processes. See Asaoka, et al, "Asphaltene Cracking in Catalytic Hydrotreating of Heavy Oils," Ind. Eng. Chem. Process Des. Dev. 1983, 242-248 and particularly FIGS. 7 and 8 of that article. However, to my knowledge no one has successfully made quantitative measurements of the amount of vanadium present in unseparated refinery feedstocks from ESR measurements.